Square Feet to Cubic Yards Calculator - Free Converter
Convert square feet to cubic yards for concrete, mulch, gravel, and topsoil. Free calculator with depth input. Get accurate material estimates instantly.
Square Feet to Cubic Yards Converter
100 ft²
3.70 yd³
How It Works
This tool converts square feet (ft²) to cubic yards (yd³) by multiplying the area by the specified depth and then dividing by 27 (since 1 cubic yard equals 27 cubic feet).
Documentation
What is a square feet to cubic yards converter?
A square feet to cubic yards converter turns a flat area measurement into a volume measurement. It multiplies an area in square feet by a depth, then converts the result to cubic yards. People use it to work out how much loose material, such as mulch, gravel, topsoil, or concrete, they need to cover a space to a certain depth.
Area and volume are not the same kind of measurement. Square feet describe a flat surface, like the floor of a garden bed. Cubic yards describe a three-dimensional space, like a pile of gravel with height. Suppliers sell bulk material by volume, because a truckload has a fixed amount of space in it. A homeowner who only knows the square footage of a project cannot order material without also knowing how deep the material needs to be.
How to calculate square feet to cubic yards
The formula has two steps. First, multiply the area by the depth to get a volume in cubic feet. Second, divide by 27, because one cubic yard equals 27 cubic feet (3 feet × 3 feet × 3 feet).
Depth is often given in inches, not feet, so it needs to be converted first. Divide the number of inches by 12.
Common depth conversions
| Depth | In feet |
|---|---|
| 1 in | 0.08 ft |
| 2 in | 0.17 ft |
| 3 in | 0.25 ft |
| 4 in | 0.33 ft |
| 6 in | 0.50 ft |
| 9 in | 0.75 ft |
| 12 in | 1.00 ft |
These are rounded for quick reference. A calculator should use the full, unrounded value for an exact result.
Example calculation
Take an area of 100 square feet with a material spread 3 inches deep.
- Convert depth to feet: 3 ÷ 12 = 0.25 ft.
- Find the volume in cubic feet: 100 × 0.25 = 25 ft³.
- Divide by 27: 25 ÷ 27 ≈ 0.93 yd³.
So 100 square feet at a 3-inch depth needs about 0.93 cubic yards of material.
A second example: the same 100 square feet spread a full foot deep (12 inches) needs 100 × 1 ÷ 27 ≈ 3.70 cubic yards. Doubling or quadrupling the depth multiplies the volume by the same factor, since area stays fixed.
Cubic yards needed for common materials
The formula stays the same for every material. Only the typical depth changes.
- Mulch, usually spread 3 inches deep: a 500 ft² bed needs 500 × 0.25 ÷ 27 ≈ 4.63 yd³.
- Topsoil, usually spread 6 inches deep for a new garden bed: a 200 ft² bed needs 200 × 0.5 ÷ 27 ≈ 3.70 yd³.
- Crushed stone for a driveway, usually 4 inches deep: a 1,000 ft² driveway needs 1,000 × 0.3333 ÷ 27 ≈ 12.35 yd³.
- Concrete for a slab, usually 4 inches deep: a 500 ft² patio needs 500 × 0.3333 ÷ 27 ≈ 6.17 yd³.
Suppliers usually sell in quarter-yard increments and cannot take back unused concrete or gravel. Many buyers round the calculated amount up and add a small buffer, often 5 to 10 percent, to cover settling, compaction, and spillage. That buffer is a planning choice, not part of the conversion formula itself.
Frequently asked questions
How many square feet are in a cubic yard?
Square feet measure area and cubic yards measure volume, so the two cannot be converted without a depth. At a depth of exactly 1 foot, 27 square feet of area equals 1 cubic yard of volume, since 27 × 1 ÷ 27 = 1.
How do I convert a depth given in inches to feet?
Divide the number of inches by 12. For example, 4 inches ÷ 12 = 0.333 feet. Use the unrounded value in the formula for the most accurate result.
How much area does one cubic yard cover?
That depends on the spreading depth. One cubic yard covers 27 ÷ depth (in feet) square feet. At a 3-inch depth (0.25 ft), one cubic yard covers 27 ÷ 0.25 = 108 square feet. At a 2-inch depth, it covers 162 square feet.
Does the formula change for different materials?
No. The formula for converting area to volume is the same for mulch, topsoil, gravel, sand, and concrete. Only the depth people typically use, and how they round the final order, differs by material.
Why do suppliers price materials by the cubic yard instead of square feet?
Bulk materials are delivered as a pile with height, not a flat sheet, so their price depends on volume, not just the footprint they cover. A dump truck or concrete mixer carries a fixed volume, which is why cubic yards became the standard unit for pricing and delivery in the United States.
Should I round my order up?
Many buyers order slightly more than the calculated volume, because loose materials such as mulch and gravel compact or settle after delivery, and irregular measurements introduce small errors. How much extra to add is a matter of judgment and depends on the material and the supplier, not on the conversion formula.